Microgrid Master-Slave Control for DER Failure Switching
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Solution Overview
Problem
Existing microgrid systems face challenges in maintaining appropriate isolated operation when a primary power adjustment resource fails, leading to disruptions in frequency control.
Innovation Solution
A system that dynamically selects a power adjustment resource with the highest storage capacity or state of charge as a master for master-slave control, ensuring continuous operation even if the initial master fails, by using a management apparatus to determine new masters based on threshold capacity or state of charge.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a prescribed power adjustment resource is determined in advance as master for isolated operation, then the isolated operation can be performed with a predetermined frequency control, but the isolated operation cannot be performed appropriately when the master resource fails to operate
Solution Approach 1:
The patent implements dynamic master resource selection by switching from a static predetermined master to a dynamic selection process that identifies an operating power adjustment resource with sufficient power storage capacity at the time of isolated operation. The management apparatus determines the master resource based on real-time operational status and power storage levels, allowing the system to adapt to changing conditions and ensure reliable isolated operation even when the predetermined master fails.
2Duration of action of moving object
If a power adjustment resource with low storage capacity is determined as master, then the master-slave control can be established quickly, but the isolated operation duration is limited
Solution Approach 1:
The patent applies preliminary action by pre-establishing selection criteria for the master resource based on power storage capacity before isolated operation begins. The management apparatus is configured to identify power adjustment resources with power storage capacity equal to or greater than a predetermined threshold, and among those, select one with the highest power storage capacity. This preliminary setup ensures long-duration isolated operation while maintaining relatively simple operational procedures.
3Device complexity
If the master resource is selected without considering power storage capacity, then the master-slave control can be established simply, but the isolated operation cannot be performed for a long period
Solution Approach 1:
The patent changes the selection parameter from simple operational status to a combination of operational status and power storage capacity. The management apparatus evaluates power adjustment resources based on whether they are operating and their power storage capacity relative to a predetermined threshold. Among resources meeting the threshold criterion, the one with the highest power storage capacity is selected as master. This parameter change extends isolated operation duration while maintaining manageable system complexity through clear selection rules.
Data Source
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AI summary
In switching of a microgrid from an isolated operation to an interconnected operation with a power grid, a CEMS server determines a first master DER and slaves based on a master plan and performs master-slave control. When the first master DER goes down, the CEMS server compares remaining capacities of power-storage-type DERs included in a DER group (S27). The CEMS server then determines a DER with the highest remaining capacity as a second master DER among the power-storage-type DERs included in the DER group (S29) and performs master-slave control (S31).